Simulation Of Logistics System And Its Application

Nowadays massive flows of materials have arisen with science and technology greatly progressing, products continuously being upgraded, and social demand rapidly changing. The flows bring about a large-scale logistics system, which is composed of multi-modal transportation, warehousing, manufacturers, retailers, wholesalers, and etc. A logistics system in operation is subject to many uncertain factors such as demand of customers, external supply of materials, internal cycle, period of supply, transportation, warehousing, and etc. These factors make each moment of the system have the corresponding relation between demand and supply. Consequently, the logistics system is very great and complicated. It has large quantities, many factors and a lot of mediate moments. Generally, researchers on logistics are supposed to solve the problems of how to study the internal structures and principles of logistics system and how to raise its efficiency and profits. Among those methods for complicated systems, simulation is quite workable. Till now there has been no complete research precedent of simulating the operation and management of the whole complicated logistics system, although simulation has been widely applied to the field of engineering and management.The dissertation chooses and develops effective simulation tools, constructs simulation models, simulates the whole logistics system, vividly displays the weak moments in logistics operation, and hints solutions to the key problems encountered when trying to reach the goal of optimization. These can help us better understand the operation of the system, optimize the management and control of logistics system, determine plans and strategies of low costs and high efficiency, and satisfy the different and particular requirements of customers.Writing the dissertation makes me get to a few points. Firstly, modem logistics is mostly characterized by systematization. Problems in logistics management should be analyzed systematically. Secondly, simulating logistics system requires effective research tools and is supposed to be premised by quantitative analysis. Therefore, the dissertation is attempting to analyze and solve problems with digital simulation in the research of logistics system.There are three purposes in writing the dissertation. The first one is to prove that digital simulation is a critical technology of studying logistics system. The second is to build digital simulation models of logistics system by choosing proper tools. The thirdis to effectively solve actual problems in logistics management with the digital simulation models that have been built.There are six chapters in the dissertation. Chapter One summarizes the current development of logistics system. Chapter Two contrastively analyzes the strengths and weaknesses of several tools for building models, with the most suitable ones chosen. Chapter Three constructs digital simulation models of logistics system. Chapter Four concerns the operation of those models and analyzes their effects. Chapter Five simulates a real case with the models. The last chapter gives the summary and prospect of the research.The main achievements of the dissertation read as follow:1) studying the current situation and problems of domestic and foreign logistics systems;2) simulating the logistics system with the means of System Dynamics and the software of VENSIM32;3) building logistics system models with MATLAB/Simulink and making digital simulation;4) analyzing the Bullwhip Effect in logistics operation with the technology of digital simulation;5) solving the discrete problem in simulation models with S Function;6) building a complete simulation model of logistics system for a certain enterprise and getting some research conclusions.The innovations of the dissertation go as follow:1) The international standard of UML is introduced into logistics simulation system, and helps realize the standardization, integration and generalization of the simulation system fr...